I'm trying to replicate option of command line ffmpeg -timecode in my C/C++ code. For some reasons the tcmd stream is not written to the output file. However the av_dump_format shows it in run time
Here is my minimal test
#include <iostream>
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libswscale/swscale.h>
#include <libavutil/opt.h>
#include <libavutil/imgutils.h>
#include <libavutil/samplefmt.h>
}
bool checkProResAvailability() {
const AVCodec* codec = avcodec_find_encoder_by_name("prores_ks");
if (!codec) {
std::cerr << "ProRes codec not available. Please install FFmpeg with ProRes support." << std::endl;
return false;
}
return true;
}
int main(){
av_log_set_level(AV_LOG_INFO);
const char* outputFileName = "test_tmcd.mov";
AVFormatContext* formatContext = nullptr;
AVCodecContext* videoCodecContext = nullptr;
if (!checkProResAvailability()) {
return -1;
}
std::cout << "Creating test file with tmcd stream: " << outputFileName << std::endl;
// Allocate the output format context
if (avformat_alloc_output_context2(&formatContext, nullptr, "mov", outputFileName) < 0) {
std::cerr << "Failed to allocate output context!" << std::endl;
return -1;
}
if (avio_open(&formatContext->pb, outputFileName, AVIO_FLAG_WRITE) < 0) {
std::cerr << "Failed to open output file!" << std::endl;
avformat_free_context(formatContext);
return -1;
}
// Find ProRes encoder
const AVCodec* videoCodec = avcodec_find_encoder_by_name("prores_ks");
if (!videoCodec) {
std::cerr << "Failed to find the ProRes encoder!" << std::endl;
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
// Video stream setup
AVStream* videoStream = avformat_new_stream(formatContext, nullptr);
if (!videoStream) {
std::cerr << "Failed to create video stream!" << std::endl;
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
videoCodecContext = avcodec_alloc_context3(videoCodec);
if (!videoCodecContext) {
std::cerr << "Failed to allocate video codec context!" << std::endl;
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
videoCodecContext->width = 1920;
videoCodecContext->height = 1080;
videoCodecContext->pix_fmt = AV_PIX_FMT_YUV422P10;
videoCodecContext->time_base = (AVRational){1, 30}; // Set FPS: 30
videoCodecContext->bit_rate = 2000000;
if (avcodec_open2(videoCodecContext, videoCodec, nullptr) < 0) {
std::cerr << "Failed to open ProRes codec!" << std::endl;
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
if (avcodec_parameters_from_context(videoStream->codecpar, videoCodecContext) < 0) {
std::cerr << "Failed to copy codec parameters to video stream!" << std::endl;
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
videoStream->time_base = videoCodecContext->time_base;
// Timecode stream setup
AVStream* timecodeStream = avformat_new_stream(formatContext, nullptr);
if (!timecodeStream) {
std::cerr << "Failed to create timecode stream!" << std::endl;
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
timecodeStream->codecpar->codec_type = AVMEDIA_TYPE_DATA;
timecodeStream->codecpar->codec_id = AV_CODEC_ID_TIMED_ID3;
timecodeStream->codecpar->codec_tag = MKTAG('t', 'm', 'c', 'd'); // Timecode tag
timecodeStream->time_base = (AVRational){1, 30}; // FPS: 30
if (av_dict_set(&timecodeStream->metadata, "timecode", "00:00:30:00", 0) < 0) {
std::cerr << "Failed to set timecode metadata!" << std::endl;
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
// Write container header
if (avformat_write_header(formatContext, nullptr) < 0) {
std::cerr << "Failed to write file header!" << std::endl;
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
// Encode a dummy video frame
AVFrame* frame = av_frame_alloc();
if (!frame) {
std::cerr << "Failed to allocate video frame!" << std::endl;
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
frame->format = videoCodecContext->pix_fmt;
frame->width = videoCodecContext->width;
frame->height = videoCodecContext->height;
if (av_image_alloc(frame->data, frame->linesize, frame->width, frame->height, videoCodecContext->pix_fmt, 32) < 0) {
std::cerr << "Failed to allocate frame buffer!" << std::endl;
av_frame_free(&frame);
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
return -1;
}
// Fill frame with black
memset(frame->data[0], 0, frame->linesize[0] * frame->height); // Y plane
memset(frame->data[1], 128, frame->linesize[1] * frame->height / 2); // U plane
memset(frame->data[2], 128, frame->linesize[2] * frame->height / 2); // V plane
// Encode the frame
AVPacket packet;
av_init_packet(&packet);
packet.data = nullptr;
packet.size = 0;
if (avcodec_send_frame(videoCodecContext, frame) == 0) {
if (avcodec_receive_packet(videoCodecContext, &packet) == 0) {
packet.stream_index = videoStream->index;
av_interleaved_write_frame(formatContext, &packet);
av_packet_unref(&packet);
}
}
av_frame_free(&frame);
// Write a dummy packet for the timecode stream
AVPacket tmcdPacket;
av_init_packet(&tmcdPacket);
tmcdPacket.stream_index = timecodeStream->index;
tmcdPacket.flags |= AV_PKT_FLAG_KEY;
tmcdPacket.data = nullptr; // Empty packet for timecode
tmcdPacket.size = 0;
tmcdPacket.pts = 0; // Set necessary PTS
tmcdPacket.dts = 0;
av_interleaved_write_frame(formatContext, &tmcdPacket);
// Write trailer
if (av_write_trailer(formatContext) < 0) {
std::cerr << "Failed to write file trailer!" << std::endl;
}
av_dump_format(formatContext, 0, "test.mov", 1);
// Cleanup
avcodec_free_context(&videoCodecContext);
avio_close(formatContext->pb);
avformat_free_context(formatContext);
std::cout << "Test file with timecode created successfully: " << outputFileName << std::endl;
return 0;
}
The code output is:
Creating test file with tmcd stream: test_tmcd.mov
[prores_ks @ 0x11ce05790] Autoselected HQ profile to keep best quality. It can be overridden through -profile option.
[mov @ 0x11ce04f20] Timestamps are unset in a packet for stream 0. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
[mov @ 0x11ce04f20] Encoder did not produce proper pts, making some up.
Output #0, mov, to 'test.mov':
Metadata:
encoder : Lavf61.7.100
Stream #0:0: Video: prores (HQ) (apch / 0x68637061), yuv422p10le, 1920x1080, q=2-31, 2000 kb/s, 15360 tbn
Stream #0:1: Data: timed_id3 (tmcd / 0x64636D74)
Metadata:
timecode : 00:00:30:00
Test file with timecode created successfully: test_tmcd.mov
The ffprobe output is:
$ ffprobe test_tmcd.mov
ffprobe version 7.1.1 Copyright (c) 2007-2025 the FFmpeg developers
built with Apple clang version 16.0.0 (clang-1600.0.26.6)
configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/7.1.1_3 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
libavutil 59. 39.100 / 59. 39.100
libavcodec 61. 19.101 / 61. 19.101
libavformat 61. 7.100 / 61. 7.100
libavdevice 61. 3.100 / 61. 3.100
libavfilter 10. 4.100 / 10. 4.100
libswscale 8. 3.100 / 8. 3.100
libswresample 5. 3.100 / 5. 3.100
libpostproc 58. 3.100 / 58. 3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test_tmcd.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf61.7.100
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0[0x1]: Video: prores (HQ) (apch / 0x68637061), yuv422p10le, 1920x1080, 15360 tbn (default)
Metadata:
handler_name : VideoHandler
vendor_id : FFMP
$
Spent hours with all AI models, no help. Appeal to the human intelligence now
No need to create a separate track. Set "timecode" metadata on either the video AVstream
or AVFormatContext. The muxer will create a timecode track.